Summary
Baloskion tetraphyllum is a member of the Restionaceae and is an important species for the rehabilitation of disused mine sites and wetland areas, and is also highly prized as a cut flower. Its use for restoration of disturbed land is, however, severely limited, due to very poor propagation success by conventional methods. A study was conducted to evaluate the potential of somatic embryogenesis for the large-scale propagation of this species. A variety of auxins (at different concentrations) were investigated for their efficacy in stimulating somatic embryogenesis. Somatic embryos were successfully induced from excised coleoptiles of B. tetraphyllum on half-strength Murashige and Skoog (1/2MS) medium supplemented with 1 μM 2,4-dichlorophenoxyacetic (2,4-D). To scale up the production, proliferation of secondary somatic embryos was achieved using primary somatic embryos as the tissue source, on 1/2MS+1 μM 2,4-D resulting in a 30-fold increase in somatic embryo, numbers. Almost all the somatic embryos developed into plants and were established ex vitro. The other auxins investigated, including p-chlorophenoxyacetic acid, indole-3-acetic acid, α-naphthaleneacetic acid, and picloram, were not as effective as 2,4-D. The age, of the explant material significantly influenced somatic embryogenesis with white, young coleoptiles (5–7 d) producing 50% more somatic embryos than green, more mature (8–14 d) coleoptiles. The protocol developed for B. tetraphyllum has the potential to be commercially viable, with an estimated 22 000 somatic embryos produced from 1 g of plant material. This research may also have a positive impact on the propagation of other important Restionaceae species.